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Color image forming apparatus having function of obtaining color information of patch

a color image and patch technology, applied in the field of color image forming apparatus, can solve the problems of long time to perform one measurement operation, colorimetric value error,

Inactive Publication Date: 2011-09-08
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This generates an error in the colorimetric value when high-accuracy colorimetry is necessary.
However, when the apparatus is stopped until the printing material sufficiently cools, it takes a long time to perform one measurement operation.

Method used

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  • Color image forming apparatus having function of obtaining color information of patch
  • Color image forming apparatus having function of obtaining color information of patch
  • Color image forming apparatus having function of obtaining color information of patch

Examples

Experimental program
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first embodiment

[0030]An image forming process in an image forming apparatus according to this embodiment will be described first with reference to FIG. 1. Photosensitive drums (photosensitive bodies) 50Y, 50M, 50C, and 50K are provided in image forming stations including toners of yellow Y, magenta M, cyan C, and black K, respectively. Latent images are formed on the surfaces of the photosensitive drums 50Y, 50M, 50C, and 50K by exposing them to laser light beams emitted by laser scanner devices 51Y, 51M, 51C, and 51K, respectively, based on an image signal sent from a controller 12 (to be described later). Further, the latent images on the photosensitive drums 50Y, 50M, 50C, and 50K are developed by toners of yellow, magenta, cyan, and black, respectively, to form toner images on them. The toner images of respective colors, which are formed on the photosensitive drums 50Y, 50M, 50C, and 50K, are primarily transferred by an intermediate transfer belt 52 serving as an image carrier which carries an...

second embodiment

[0049]An image forming apparatus according to the second embodiment will be described below. The basic configuration in the second embodiment is the same as in the first embodiment, and a description of the same parts will not be given. A feature of this embodiment lies in changing the patch array in accordance with the type of printing material. Some printing materials contain fluorescent components in large amounts while others contain less fluorescent components. The temperature dependence of the spectral reflectivity differs between a printing material containing a fluorescent component in large amounts and that containing less fluorescent component. The temperature dependence of the spectral reflectivity means herein the degree of variation in color information (information on ΔE), that occurs in response to a change in temperature (for example, a rise in temperature) by a predetermined amount, and the larger the variation, the higher the temperature dependence.

[0050]FIG. 9A sh...

third embodiment

[0054]An image forming apparatus according to the third embodiment will be described below. FIG. 11A is a functional block diagram of a control unit 10 in the image forming apparatus shown in FIG. 1, according to this embodiment. In this embodiment, a colorimetric value temperature correction unit 15 is added to the configuration according to the first and second embodiments. Thus, color information obtained by colorimetry is corrected in accordance with the temperature of a color patch in the colorimetry. Based on the thus corrected color information, a color conversion LUT generation unit 16 of an arithmetic unit 13 updates a color conversion LUT 14a. Note that the image forming process in this embodiment is the same as in the first embodiment, and a description thereof will not be given. In this embodiment, the arithmetic unit 13 obtains a correction coefficient by looking up a temperature characteristic LUT 15a of the colorimetric value temperature correction unit 15, in accorda...

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Abstract

An image forming apparatus uses the difference in time taken for each patch to reach a color sensor, which occurs upon reversing the conveyance direction of a printing material. Due to this difference in time, the temperature of the printing material in detection by the color sensor differs among the respective patches. The error of a colorimetric value due to thermochromism is reduced by placing a patch with a colorimetric value which has a low temperature dependence so as to be detected earlier, and a patch with a colorimetric value which has a high temperature dependence so as to be detected later.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a color image forming apparatus which forms a color image.[0003]2. Description of the Related Art[0004]In recent years, a color image forming apparatus which is typified by, for example, a color printer and a color copying machine and adopts, for example, the electrophotographic or inkjet scheme must output higher-quality images. To meet this requirement, Japanese Patent Laid-Open No. 2003-084532 proposes a color image forming apparatus including a color sensor located downstream of a fixing unit. The color sensor irradiates a patch formed on a printing material with light to obtain its color value (color information) from the light reflected by it. The color image forming apparatus adjusts the tone of a toner image formed on the printing material, in accordance with the output from the color sensor.[0005]Upon colorimetry of the patch formed on the printing material, the colorimetric val...

Claims

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Application Information

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IPC IPC(8): G03G15/00
CPCG03G15/00G03G15/5062G03G15/0105G03G15/2039G03G15/55
Inventor USUI, MASATAKEKITA, HIROSHIEBIHARA, SHUN-ICHIYOKOYAMA, KEN
Owner CANON KK
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